Sludge and condensate discharge for steam peelers



P 4, 1951 w. DE BACK 2,567,103,

SLUDGE AND CONDENSATE DISCHARGE FOR STEAM PEELERS. V

2 Sheets-Sheet 1 Filed Jan. 6. "1949 4 INVENTOR WILLIAM DE BAGK ATTORNEY W. DE BACK Sept. 4, 1951 SLUDGE AND CONDENSATE DISCHARGE FOR STEAM PEELERS Filed Jan. 6. 1949 2 Sheets-Sheet 2 R O T N E V m mug! DE ans/r ATTORNEY Patented Sept. 4, 1951 SLUDGE AND CONDENSATE DISCHARGE FOR STEAM PEELERS William do Back, San Jose, 'Calif., assignor to Food Machinery and Chemical Corporation, San Jose, Calif., a corporation of Delaware Application January 6, 1949, Serial No. 69,434

9 Claims. 1 The present invention appertains to a continuous steam peeler for peeling fruit and vegetables, and relates more particularly to an automatic blow-off device for removing sludge and condensate from the same.

The present invention is intended for use with a peeler of the type wherein unpeeled fruit or vegetables, such as potatoes, are inserted through a steam tight rotary feeder into the lower end of an inclined cylindrical steam chamber. A spiral conveyor is mounted coaxiallyof the chamber, and is power driven to rotate about its axis and convey the vegetables toward the upper end. of the chamber where a steam tight discharge is provided to remove the peeled-vegetables from the chamber without loss of steam pressure in the chamber;

As the fruit or vegetables are thus fed into,-

advanced upwardly through, and discharged from the'steam chamber, they'rub against each other, the conveyor flight, and the walls'of the chamber, so that besides the condensate large quantities of skin of the treated products, as well' as foreign matter introduced with the same, ac-

cumulate in the lower part of the chamber and form a sludge or sediment, which is undesirable and interferes with the efiicient operation of the machine. The accumulation of sediment is especially aggravated when the fruit or vegetables are sprayed with water during their processing in the treating chamber.

To discharge the condensate and to remove this sediment or sludge from the treating chamber it has heretofore been the practice to provide the chamber with an ordinary sludge vent which could be opened to the atmosphere from a low point in the chamber, with a valve, such as an ordinary globe or gate valve, mounted to control the flow therefrom. This valve was opened from time to time to blow the sludge and condensate from the chamber. However, the valve operation was uncertain, and required excessive maintenance under the severe operating conditions of high temperature and pressure and the abrasive and clogging action of the materials contained in the sludge. This resulted in severe sludging up of the chamber and abrasion of the internal parts of the mechanism, which required excessive maintenance and tended to detract materially from the otherwise excellent operating characteristics of this type of peeler.

It is, therefore, an object of the present inventionto provide an improved automatic sludge and condensate discharge for continuous steam peeling machines.

Another object is to provide a sludge and con densate remover fora steam pressure vegetable 'peeler, which includes a rotary element adapted to agitate and remove sludge and condensate from a low point of the treating chamber of the peeler.

Another object is to seat a rotatably mounted sealing element in the low end of an inclined Another object is to mounta pressure sealing element for normally 'freerotative and limited angular adjusting movement on the shaft of a screw conveyor rotatably and coaxially mounted within a cylindrical treating chamber, and to drive the element by means operatively connecting the plate to 'a spiral flight-0f the conveyor without restricting the plate against free angular adjusting movement.

These and other objects and advantages of the invention will become apparent from the follow ing description and the accompanying drawings, wherein: I

Fig. 1 is a somewhat diagrammatic side elevation of an inclined-continuous pressure steam peeler provided with the sludge and condensate remover or the present invention, certain arts being broken away while others are shown in section.

Fig. 2 is an enlarged fragmentary transverse sectional View taken along line 22 of Fig. 1.

Fig. 3 is a fragmentary'longitudinal'vertical sectional view takenalong line 3'3 of Fig. 2.

Fig. 4 is a fragmentary elevational view showing the inner face of the pressuresealing, and sludge and condensateremover plate, forming part of the-present invention."

Referring to the mechanism shown in Fig. 1, the inclined steam peeling mechanism l0 comprises a-steam or treating chamber I l with a uniform cylindrical bore I2 therein'mounted with the axis of the bore'disposed at an inclined angle of approximately 20 from the horizontal; The

steam chamber is supported on a base [-3 of conventional construction.

A drive motor 14 is mounted on the central cylindrical body portion [5 of the steam chamber. The motor I4 is connectedt-hrough suitable drive mechanism to drive the various mechanisms'to bedescribed later herein. The steam chamber" H is provided with a usual pressure gauge l7, safety valve [8, and manual pressure release valve IS.

A pair of end members 20 and 2| are mounted one on each end of the central body portion IS. The end members may be of cast or welded construction, and are secured to the central body portion as by cap screws 22. The steam chamber end members 20 and 2| are similar to each other, but are mounted in relatively inverted positions. Each of the end members has a bore portion 23 (Fig. 3) which is coextensive with the cylindrical bore l2 of the central body portion l5.

The outer ends of the end members 29 and 2| (Fig. 1) are closed by-end closure members or heads 24 and 25, respectively. These heads also may be of cast or welded construction. The head 25 on the upper end of the steam chamber may be of any suitable construction, but the lower head 24 has distinction features which will be brought out later herein.

A spiral or screw conveyor 21 has an axial shaft 28 which is mounted for rotation in bearings 29 supported in yokes 30 mounted by bolts 3! to extend outwardly from the heads 24 and 25, respectively. The bearings 29 may be thrust type roller bearings.

The conveyor shaft is sealed to the heads against stem loss by usual packing glands 32 (Fig. A drive gear 33 (Fig. 1) is keyed to the projecting upper end of the conveyor shaft and is driven by conventional drive mechanism (not shown) from the motor l4. A rotary feed valve F and discharge valve D are associated with the chamber end members 20 and 2|, respectively. These valves are of similar construction and only the lower one, shown in detail in Fig. 1, will be described.

The feed valve F comprises an annular rotor or valve chamber 34 formed integrally with, and extending upwardly of, the lower end member 20. This rotor chamber is provided with an inlet opening 35, which is open to the atmosphere, and an outlet opening 36 which establishes communication between the housing 34 and the bore 23 of the end member 20.

A pocketed article feeding rotor or valve 31 is rotatably mounted in the chamber 34 with blades 38 thereof in sealing engagement with the peripheral wall of the rotor chamber. Rotor chamber side plates 39 are mounted in sealing engagement with the rotor 31, one plate being mounted on each side of the rotor chamber 34. The feed rotor 31 is driven by the motor [4 in any convenient manner, and in synchronism with the other parts of the mechanism. The spaces between the rotor blades thus form individually sealed pockets 40 for transferring articles, such as fruit or vegetables to be peeled, from the atmosphere into the steam chamber without loss of steam pressure.

The food products 4| to be peeled are fed by suitable accessory equipment, not shown, into the inlet opening 35 in quantities sufficient to fill each of the pockets or compartments 4!] to approximately '70 per cent of its capacity. A

similar but inverted arrangement is provided by the discharge valve D associated with the upper end member 2| to discharge the peeled articles from the steam chamber.

Referring now to the automatic sludge and condensate remover which is a principal feature of the present invention, the lower end portion of the axial conveyor shaft 28 (Fig. 3) is reduced, as shown at 43, and a collar 44 is fitted onto the reduced end portion of the shaft; This collar is spaced inwardly from the inner end of a hub portion 45 of the lower head 24, in which the packing gland 32 is mounted, by a distance substantially greater than the thickness of a rotary sealing plate 41. This sealing plate is mounted loosely on the reduced shaft portion 43 to be free for limited tilting movement relatively thereto.

The lower head 24 has a bell-shaped central portion 48. A relatively thick, flat, annular backing plate 49 of suitable material, such as metal, is mounted in a seat formed by rabbeted grooves 50 and 5| formed in the hub 45 and an inner marginal edge of the bell-shaped portion 48, respectively. A pair of set screws 52 and 53 are screwed into threaded holes drilled half in the hub and half in the backing plate to anchor the backing plateagainst rotation.

A plurality of plugs 54 are screwed into threaded holes in the bell-shaped portion of the lower head 24. These plugs are removable to admit the insertion of a common drift pin 55, indicated in dot-dash lines in Fig. 3, when it is desired to remove the backing plate 49 upon disassembly of the apparatus.

The diameter of the backing plate 49, and, therefore, the diameter of its marginal seat 5| in the head bell portion 48, is slightly greater than that of the steam chamber bore l2. A shallow rabbeted groove 51, therefore, also is provided marginally around the end of the corresponding bore 23 in the end member 20. This arrangement retains the backing plate against substantial axial displacement except by removing the lower head 24.

The backing plate has a large threaded remover opening 58 (Fig. 2) and a small threaded remover opening 59 therethrough near the lower marginal edge thereof, when mounted, as illustrated in Fi s. 2 and 3. These openings are located axially inwardly from a threaded opening 60 in the bell-shaped portion 48 of the lower head 24. The diameters of the openings 58 and 59 are a matter of design, and may be computed readily by one familiar with the art upon reading the description of their operation and functions as set forth herein. 7

The opening 69 in the lower head 24 is substantially larger in diameter than either of the openings 58 or 59. The clearance of the bellshaped portion 48 from the backing plate 49 is sufficient to admit the threaded insertion of either a theaded plug 6| to close the larger opening 58, or a similar type smaller plug, not shown, to close the smaller opening 59. Thus, either of the openings 58 or 59 can be closed selectively as required before screwing a sludge and condensate remover pipe 62 into the threaded opening 69 in the lower head. A manual control valve 63 is mounted to control fluid flow through the pipe 52. During normal operation of the apparatus, however, this valve is left open.

The inner face of the backing plate 49 has a circular recessed seat 64 therein, surrounded by an annular marginal rim 65. The rotatively mounted sealing plate 4'! is seated on the recessed seat 64 on the backing plate to have sealing engagement therewith, and overlies the plug receiving openings 58 and 59. The sealing plate 41 is of sufficiently smaller diameter than the seating recess 54 to provide a substantial marginal clearance 68 between the periphery of the sealing plate and the rim 65 surrounding the recess.

- The plug receiving holes 58 and 59 are located iwith theinouter marginahwalls-rbotlr at. the same raidiail distanceifrom thev axis of -theaeonveyor 21. f Qn'e or ":more'radiallw'disposedr*groo'ves: 69 CFig. 3) 'aretformed: in: the :rear or sealingiac'e of the sealing plate 41. .These'g'rooves extend from the periphery' of the: s'ealing plate to a point-radially .inwardlyf from the outer edges of both; the plug "receiving holes: 58 and 59. :They thus provide rwpassages 'opening from a low-Zone of the steam 'ticham'ber into the plug receiving holeszupon each "ffull rotation of the sealing plate.

vii-The loosely mounted -rotative sealing :plate 41 'v-i-has=ana'ngle bracket secured todtheinneriace ":thereof; as'byri'vets 11. The bracket is mounted isubstantiallys' radially of} and 2 with its outer end -rneai the peripheryl of --the' *seal-ing= iplate. waThe arivets r preferably are: of': softermateria1 tha11 'f-ieithenthe backing plate on th'esealing-plateyand heir-heads toward the backing plate-arecounterunlc to retain thesea'l-between the sea-lingiplate v-aand; the-'abacking 'plate. l The angle bracket I 0 r isnpositioned to-b'e enga'ge'd'by the 'radiall y dis- 'wposed'lower end' 12 or the spiral' fiightl'lii of the screw :conveyor. 1 Thus; as the Pconveyor is='--ro- 1: 1 *tated by'th'e motor: I 4 to move material upwardly rmalon'g thesteam phamber' H; by 'ar-usua-rdrive r mechanism including the'drive gear 33;the loose- I" mounted sealin'g :plate fl 'als'o will be rotated -"bythe' engagement "between the end 12- of'the rflight- T3 and the anglebracket l I].

i Rotation: of: the sealing :plate 50311186913119 outer ----:end of the bracket 10 to swing'adjaoentt the wwall of=the bore: 23 of :thelower endHme'm'berIZG rand 1 thus tends tO eSti-l. "up' 'rany sludge? and con- 1 rdensatein 'the bottorxr o'tithe steam chamber at each revolution" of -the sealing 'platex" *This'prevents- -the sludge from eaking and 'keeps it in w condition foreasy" removal.

'5 group of r'emover holes lMarerdr-illed in -an ra-reaof ther-sea'ling'aplate to pass -over *an'df-open ingo the" larger plug receiving hole 58;":up'on each re revelation of the sealing "platefwrSom'e 0-f '-lthese v holesalsoare positioned to open' into the smaller plug Teccivingholes 59 during each -sucii revolution.= Theseholes' in th'e sea'ling =plateipreferably are rrelatieely small': as compared tot-the- =larger plug'receivingfihole 58 to prevent an-y l'arge pieces ofv the-products undergoing treatment front-being blownwout: of thes'ey'linder with the sludge and T :conden'sate.

When the steami'peelen l-n is to 'be used in conwiiunctionhvith a' water spray; of t'he"-usual type -:of washing "away *p'eelings and other matter removed-' during: pro'eessing, the larger plug 17 58 will'be removed; and th'e smallerhole 59' will be .i plugged; "Whenthe device. is? to be 'u'sed w'ith steam alone, however,Fthei larger 'holel 58 wi1l 'be :plugged,'as;shoWn in'Fig. 2,:an'd the 's'maller hole 59 Wi1l"b'e' =1eft open.

Operation Before,-operating the :peelerg: the 'dec'isi'on must bemade whether or =-not a waterrsprayewash 1 willbe used and :the plugs adjusted?as'isetrforth in the preceding 'paragraph.-- When a ehangei in the plug arrangement is to :be made; the pipe 62 a. must be removed to provideaccess tirthe p'lugs. The changing of plugs is-necessary only atinfrei-.quentintervals; for example; when-changing .from one type of fruitor vegetable-atoi anbther; With the selected plug arrangement: madeand the manually operated valve as open; vthe =-motor M is energized, steam is-admitted to thewhamber. LL-andthe: pressure is: brought to a required readinglon the gauge l 1.

mice

-The food= products to: be peeled; for exaiiiple, potatoes; are fed into the inlet 35 preferably in b'atches adaptedto fill eachcompartment 40: of the "rotary**feed= valve to a degree where the s-products wilrnot be damaged or Sheared 'ofPbY he rotative action of the valve. As each succes- 'sive pocket-load of the food products drops by gravity through the lower opening 36 inthe 'rotary housing 34,-the products are exposed to the isteam and'drop" to the bottom of the inclined 'csteam-"chambef' l0. Here the conveyor 2'! prorpelszthe articles upwardly along the inclinedbottom of the'steamchamber toward its upper end, 'rolling them about and exposing all portions "thereof to the heat of the steam chamber. They then are discharged'through the upper'end'assembly 42 in a manner generally similar to that described for the feed valve. The rate of "disch'arge conforms generally with that of'ohargjng As the screw conveyor 2! is rotated by the --motor through thegear 33 and associated mechanism "(not/shown), it rotates the loosely mounteft sealing-plate A'TWhich is urgedtowardthe --baekir1g plate 49 by the unbalance between'steam pressure' m the chamber H "and atmospheric pressure beyond the unpluggedhole 58 or 59;'as the case may be. The manually controlled valve E3 fn'the'removerpipe' 62 being open, the interior of the bell housing portion 48 of'the lowerhad 24 beyond the backing plate will be open" to the atmosphere.

"As the radial grooves 69'*are"swunginto'regis- =ter"successively vviththe unplugged'hole 58 or59 in-thebacking pl'ate; as the case may be, theunbalance of pressurebetweenthe'interior of'the I "steam chamber and the atmospheric pressure-beyondthe unplugged hole blows "sludge or hondensat from"theverydowermost zone'of the steam chamber'upwardl'y through-theipassa'ges providedby the grooves 69"'"and "outwardly 'through'theunplugged h'ole; 'nlsoyoneach'revolu'tion' of 'the'-"sealing" p1ate- 41, as the "holes 14 therein register with the unplugged hole'in the e's-backing platen accumulated condensate-"and sludge will be blown out throughth'e unplugged hole in a-manner'similar to that described for the --"grooves.

*Since this "cleaning action "occurs upon" each *60' revolution o'fthesealing plate 41; and since the stirring 'action' of" the angle bracket preventscaking of sludge, the steam chamber thus is'kept free from 'accretions' offoreign matter and peelings which hitherto have been a'source of trouble ii and annoyance with-"this type" of mechanism.

:Due to-the high temperatures to" which the sealing plate and backing plate' are exposed, "and the factthat nogre'ase' or other lubricantwhich :mi'ght" contaminate "the food productsbeing *processedcan' be employed toreduce' friction between these plates; 'the'backing plate49 prefer- -ably is made of bronze and "the" rotary sealing plate 61 of stain'less steel.

T :The only effective pressure area on the sealing 65' plate Will be over areas thereof'where'tliepres- '-'sure o'n the outer face thereof is're'du'cediby con- "nection to the atmosphere through -="'thei:=un-

plugged hole-'58 or 59. Therefore, this'ieffe'ctive pressure vvill'act principally ori the'lo'wer per- 1 7mtionof the sealing' plate"and"willtend to-"concentrate' the wear-between the" sealing plate alnd the backing' plate on" the lower portion ofcathe "backing plate; Since I the sealing plate is 'rotated constan-tly s'duringlroperation i of Ether apparatus,

i 7 wear :one theisealingeplate .willibeidis'tributed but will be greater toward its outer margin. However, the relatively loose mounting of the sealing plate on the conveyor shaft permits it to tilt relatively to the axis of the conveyor and thus continues to maintain itself and the backing plate in sealing contact with each other even after a considerable amount of wear has occurred between these plates.

The device comprises a simple, fully automatic, arrangement for keeping the peeling chamber cleanand free from sludge and condensate with a minimum loss of steam. It requires no expensive accessory drive mechanism and the sealing parts automatically tend to keep themselves seated even after the occurrence of a substantial amount of wear. Since such wear as does occur is between inexpensive and readily replaceable parts, maintenance cost is negligible. When necessary, it usually need be performed only at the usual inspection and overhaul before each canning season.

While I have illustrated and described a preferred embodiment of my invention, it will be understood by those familiar with the art that the arrangement is capable of some modification without departing from the spirit of the present invention and the scope ofthe appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. A sludge and condensate discharge for a steam peeler having an axially inclined cylindrical steam pressure chamber with a power driven rotary element mounted therein, power drive means operatively connected to rotate said rotary element, and means for introducing products into and removing them from said steam chamber, said chamber having an exteriorly discharging opening below a maximum desired sludge level therein; said discharge comprising a rotative sealing plate adapted to be mounted coaxially of said power driven rotary element to be forced into sealing condition over said discharge opening by pressure within the steam chamber, and drive means operatively interconnecting said power driven rotary element and said sealing plate, said sealing plate having a hole therein at a radial distance from the rotative axis of the sealing plate to open into said discharging opening upon each complete rotation of the sealing plate.

2. A sludge and condensate remover for a steam peeler having an axially inclined cylindrical steam pressure chamber with a power driven rotary conveyor mounted coaxially therein, power drive means operatively connected to rotate said rotary conveyor and means for introducing articles into and removing them from said steam chamber, said chamber having a pair of different sized ex- -teriorly discharging openings below a maximum 1 being smller than either of said exteriorly discharging openings, the holes being located at different radial distances from the rotative axis of the sealing plate to open into one of said discharging openings upon each complete rotation of the sealing plate, some of said holes being veyor, and means for introducing articles into and removing them from said steam chamber; said remover comprising a backing plate adapted to be seated removably in a lower end portion of such cylindrical chamber to have a portion thereof located below a maximum desired sludge level in said chamber, said backing plate having .two difierent sized exteriorly discharging openings therein with their outer marginal walls located below such maximum sludge level and substantially equi-distant from the rotative axis of the conveyor, means for closing, selectively, one or the other of said openings, a rotative sealing plate mounted loosely coaxially of said power drive rotary element to overlie said openings in the backing plate, and adapted to be forced by steam pressure within the chamber into sealin relation with the backing plate, and drive means interconnecting said power driven rotary element and said sealing plate, said sealing plate having a grouped plurality of holes therein, each of said grouped holes being smaller than the larger of said exteriorly discharging openings in the backing plate, the holes being grouped between radial distances from the rotative axis of the sealing plate to open into the larger of said discharging openings upon each complete rotation of the sealing plate, some of the grouped holes being within, and some being wholly beyond the radial limits of the smaller of said discharge openings.

4. A sludge and condensate remover for a steam peeler comprising, in combination with a peeler having an axially inclined cylindrical steam pressure chamber with a rotative conveyor mounted coaxially therein and having power drive means operatively connected to rotate said conveyor about its axis; a backing element mounted in the low end of the steam chamberand having a dis charge opening below a maximum desired sludge and condensate level therein, and a sealing plate rotatably mounted coaxially with the conveyor to overlie and seat on the backing element normally to seal said discharge opening, said sealing plate having a passage opening from the interior of the steam chamber at a point adjacent the marginal edge of the sealing plate into the discharge opening in a. predetermined rotative position of the rotor plate, thereby to blow sludge and condensate from the steam chamber upon each rotation of the rotor plate.

5. A sludge and condensate remover for a steam peeler comprising, in combination with a peeler having an axially inclined cylindrical steam chamber with a rotative conveyor mounted coaxially therein and having power drive Tmeans operatively connected to rotate said conveyor about its axis; a backing plate removably mounted in the low end of the steam chamber and having a discharge opening below a maximum desired sludge and condensate level therein, and a'sealing plate rotatably mounted coaxially with the conveyor to overlie and seat on the backing plate normally to seal said discharge opening, said sealing plate having a radial groove in the face thereof seating on the backing plate to form a passage opening from the steam chamber at the marginal edge of the sealing plate into the discharge opening in a predetermined rotative position of the rotor plate. thereby to blow sludge and condensate from the steam chamber upon each rotation of the rotor plate.

6. In a steam peeler having a steam pressure echamber with a sludge outlet in a low portion thereof, a pressure sealing element mounted for inormally free rotative and angular tilting adjusting movement inwardly over said sludge outlet, said pressure sealing element having a pas- :sage therethrough adapted to communicate between the interior of the steam chamber and the sludge outlet in a predetermined rotative position of the sealing element, and rotative drive means operatively connected to rotate said seal- :ing element without restricting substantially its freedom for angular tilting adjusting movement.

7. In a steam peeler having an axially inclined cylindrical steam pressure chamber with a sludge outlet in a low portion thereof, a rotative ,shaft journaled axially of said chamber, a pressure sealing element loosely mounted on said :shaft for normally free rotative and angular adjusting movement thereon inwardly over said sludge outlet, an abutment on an inner face of said pivotally mounted element, a radially projecting element secured to said shaft and positioned to have abutting driving relation with said abutment, said pressure sealing element having a passage therethrough adapted to communicate openly between the interior of the steam chamber and the sludge outlet in a predetermined rotative position of the sealing element, and rotative drive means operatively connected to rotate said shaft thereby to rotate said sealing element without restricting substantially its freedom for angular adjusting movement.

8. In a steam peeler having a cylindrical steam pressure chamber with a sludge outlet in a low portion thereof, a rotary conveyor journaled axially of said chamber, a pressure sealing element loosely mounted for normally free angular adjusting movement inwardly, and in sealing relation over, said sludge outlet, and drive means operatively connected to said rotary conveyor and to said sealing element to rotate said rotary conveyor and periodically to move said sealing element relatively to said pressure chamber and out of sealing relation to said sludge outlet without restricting substantially its freea dom for angular adjusting movement.

9. A sludge and condensate remover for a steam peeler having an axially inclined cylindrical steam pressure chamber with a power driven rotary conveyor mounted coaxially therein, power drive means operatively connected to rotate said conveyor, and means for introducing articles into and removing them from said steam chamber; said remover comprising a backing plate adapted to be seated removably in a lower end portion of such cylindrical chamber to have a portion thereof located below a maximum desired sludge level in said chamber, said backing plate having two difierent sized exteriorly discharging openings therein with their outer marginal walls located below such maximum sludge level and substantially equi-distant from the rotative axis of the conveyor, means for closing selectively, one or the other of said openings, a rotative sealing plate mounted loosely coaxially of said power driven rotary element to overlie said openings in the backing plate, and adapted to be forced by steam pressure within the chamber into sealing relation with the backing plate, and means drivingly interconnecting said power driven rotary conveyor to the loosely mounted sealing plate with said sealing plate free for tilting movement relative to the conveyor axis of rotation, said sealing plate having a grouped plurality of holes therein, each of said grouped holes being smaller than the larger of said exteriorly discharging openings in the backing plate, the holes being grouped between radial distances from the rotative axis of the sealing plate to open into the larger of said discharging openings upon each complete rotation of the sealing plate, some of the grouped holes being within, and some being wholly beyond the radial limits of the smaller of said discharge openings.

WILLIAM DE BACK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,078,420 Davies Nov. 11, 1913 1,163,687 Purvis Dec. 14, 1915 1,735,392 Hiller Nov. 12, 1929 

